[TW-1305] Make tasks with due:someday less urgent than task without a due date

_Tobias Mueller on 2014-04-15T13:26:59Z says:_

When creating a task with due:someday it is considered more important than tasks without a due date set.

I think it is not intuitive as I set due:someday to indicate that I don't want to look at that task until I have some spare cycles. Until that is the case, I usually want to work on every other task, including those for which I did not set a due date.